Plot hole: Vaughan discovers Lauren is a mole when he goes through her briefcase and discovers the wig, gun and fake passport she used in Germany a few hours before - surely even the worst secret agent in the world would have enough sense to get rid of such incriminating evidence as soon as possible, and not carry it back to the USA (sneaking it onto a plane, presumably) and leaving it in the room where the man you're lying to sleeps. Lauren is a highly skilled agent, if the Covenant selected her for a mission this important, so it's out of character (without an explanation) for her to be so sloppy.
Other mistake: Near the end of the show they are supposed to be in a parking garage in Spain, but there are way too many American cars.
Continuity mistake: In this episode Nadia Santos tries to find out who's the baby that her mother Irina Derevko is holding on a picture. She first shows it to Jack Bristow and later to Arvin Sloane. Later Jack asks to see to picture again and tells Nadia it's Irina's niece. At the several moments the picture is visible the picture is flipped, showing the baby on the left arm or right arm of Irina. (00:29:55 - 00:36:35)
Visible crew/equipment: Jack meets Irena at the beginning of the episode. When they start to dance, Irena kisses Jack. Right before Irena pulls away, above her head is a boom mic. It lasts until the next shot when the camera is focused more on Irena.
Answer: Bad Day by R.E.M.